Broadband sheet antenna



Feb. 6, 1962 J, BEEVER 3,020,550

BROADBAND SHEET ANTENNA Filed Sept. 28, 1959 54 JAGK BEEVER ATTORNEY nite tates atent fitice 3,029,550 BROADBAND SHEET ANTENNA Jack Beaver, Philadelphia, Pa., assignor to Jerroid Elecironies (Iorporation, Philadelphia, Pin, a corporation of Delaware Filed Sept. 28, 1959, Ser. No. 842,832

4 Claims. (ill. 343--795) This invention relates to an antenna of the modified dipole type utilizing materials of minimal thickness in the plane at right angles to the magnetic fields of the incident radiation.

The primary object of the invention is to provide an antenna of the character described with uniform directivity across its usable bandwith, in order to remove the necessity of redirecting the antenna when receiving broadcasts of different frequency from the same general direction, as is common in receiving television broadcasts.

Another object of the invention is to provide an antenna for receiving TV or FM broadcasts which can be placed under a rug or in an attic and whose insensitivity to standing waves in space alleviates the difiiculty encountered with conventional indoor antennas of the telescoping dipole or monopole type, when persons moving in the vicinity of the antenna disturb the reception.

Another object of the invention is to provide a broadband antenna of such configuration and design as to possess a nominal impedance of 300 ohms, a gain of not less than zero db with reference to a tuned dipole and a maximum voltage standing wave ratio or V.S.W.R. of 1.7 across its operating frequencies of 54 to 108 mc. and 174 to 216 mc.

Yet another object of the invention is to provide a broadband antenna which may be readily and easily manufactured of inexpensive materials.

These and other objects or" the invention will become more apparent as the following description proceeds in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a plan View of one form of the invention;

FIGURE 2 is a plan view of a second form of the invention; and

FIGURE 3 is a plan view of a third form of the in- Vention.

Specific reference is now made to the drawing wherein similar reference characters are used for corresponding elements throughout.

Referring first to FIGURE 1, the same comprises a thin sheet of insulating material it such for example as paper, upon which the antenna is aflixed. In this case the antenna comprises highly conductive metallic paint or ink, such as silver ink, which is applied to the insulating sheet by any suitable means in a modified dipole configuration. Basically, the antenna comprises two conductive right triangles 12 and 14 having horizontally aligned bases 16 and 18, altitudes 20 and 22 and hypotenuses 2d and 26, the apexes of the acute base angles being adjacent each other and constituting connecting points 28 and 30 (here shown as conductive eyelets) adapted for connection to wires leading to the antenna input posts of a TV or FM receiver (not shown).

A conductive line or band 32 of thickness greater than the thickness of the peripheral lines of the triangles joins the apexes of the triangles opposite the bases and extends parallel thereto. A further conductive line or band 34 of thickness approximately that of line 32 extends parallel to said line, is spaced a short distance therefrom and terminally joins the hypotenuses 24 and 26. A network of crossed conductive paths 36 is provided in each triangle consisting of paths 38 extending radially from each connecting point to each altitude and further paths 40 extending across from each altitude to each hypotenuse,

producing an electrical eiiect of a solid conductive surface over the entire area of each triangle.

The modification of FIGURE 2 includes the same insulating sheet 10 and an antenna of the same modified dipole configuration as above described except that it is made of metal foil laminated or otherwise affixed to the sheet. Accordingly, the two members 42 and 44 are solid metal foil right triangles whose bases 46 and 48 are in horizontal alignment and whose acute base angle apexes are adjacent each other as at 50 and 52 and constitute connecting points for antenna Wires. A foil strip 54 terminally joins the apexes opposite the bases of the triangles and extends parallel to the bases and a further foil strip 56 extends closely adjacent and parallel to the first strip and terminally joins the hypotenuses of the tri angles The modification of FIGURE 3 is identical with that of FIGURE 1 except that there is no insulating sheet and the antenna is made of highly conductive wire. Accordingly, the members 58 and 60 are right triangles whose hypotenuses, bases and altitudes are made of wire and the network of crossed conductive paths 62 within the triangles are also made of wires which are conductively connected to each other and to the altitudes, hypotenuses and connecting points 64 and 66 of the triangles. The first line 68 conduetively connecting the apexes opposite the bases and the second line 70 conductively connecting the hypotenuses adjacent said apexes are parallel pairs of wires. Any suitable insulating frame may be employed to support the assembled wires, here shown as a U-shaped wood frame '72 to which the wires are secured by appropriate staples 74.

To be operative for the VHF, TV and domestic FM frequencies of 54 to 108 me. and 174 to 216 mc., the antenna must have an impedance of 300 ohms, a maximum V.S.W.R. of 1.7 across its operating frequencies and a gain of not less than zero db with reference to a tuned dipole. To effectuate this, certain parameters must be employed in the modified dipole design of the present antenna. The distance a between the right angle apexes=.4 the length b of each altitude=.16)\:t10%, and the distance c between the facing inner edges of the conductive lines 32 and 34 (also the foil strips 54 and 56 and the wires 68 and 70)==.014 \:10%, where =wavelength in air at mean frequency, first harmonic. In actual practice, the distance between the connecting points (28, 3t 50, 52; 64, '66) is also .0l4hil0% and the width d of the conductive lines 32 and 34 (also the foil strips 54 and 56 and the wires 68 and 70)=.003 \i10%. When networks of conductive paths 32 and 62 are used, in the modifications of FIGURES 1 and 3, each nonconductive area 76 in the network must have a dimension in any direction no greater than O.l)t- -10% where A=wavelength in air at mean frequency, third harmonic.

Using the above parameters, a commercially feasible antenna of the modified dipole design described herein possesses the following dimensions: (1:72", b=25",

0:2" and d= /2".

While preferred embodiments of the invention have here been shown and described, it is to be understood that skilled artisans may make minor variations without departing from the spirit of the invention and scope of the appended claims.

I claim:

1. A broadband antenna covering 54 to 108 me. and 174 to 216 mc. frequencies comprising a sheet of insulating material, a pair of right triangles afiixed thereto with their bases in horizontal alignment and the apexes at the acute base angles adjacent each other, the latter constituting connecting points adapted for electrical connection to wires leading to the antenna posts of a receiver, the peripheries of said triangles being conductive,

a first conductive line parallel to said bases and connecting the apexes opposite said bases, a second conductive line parallel to and spaced from said first conductive line and terminally connected to the hypotenuses of said triangles, and a network of crossed conductive paths in each triangle establishing contact between the connecting point and the altitude thereof, the overall length of said bases being 0.4%, the length of said altitudes being 0.16kil0% and the space between said first and second conductive lines being 0.010110%, where )\=wavelength in air at mean frequency, first harmonic, each non-conductive area of said network of conductive paths in said triangles having a dimension in any direction no greater than 0.l)\il0% where t=wavelength in air at mean frequency, third harmonic.

2. The antenna of claim 1 wherein said triangles, first and second conductive lines and said network of conductive paths in said triangles are made of highly conductive metallic ink.

3. A broadband antenna covering 54 to 108 me. and 174 to 216 me. frequencies comprising a sheet of insulating material, a pair of metal foil right triangles afiixed thereto with their bases in horizontal alignment and the apexes at the acute base angles adjacent each other, the latter constituting connecting points for electrical connection to wires leading to the antenna posts of a receiver, a first band of metal foil parallel to said bases connecting the apexes opposite said bases, and a second band of metal foil parallel to said first band and terminally connected to the hypotenuses of said triangles, the overall length of said bases being 0.4/\, the length of the altitudes of said triangles being 0.16 10% and the space between said first and second bands being 4 0.014Ai10%, Where A=wavelength in air at mean frequency, first harmonic.

4. A broadband antenna covering 54 to 108 me. and 174 to 216 mc. frequencies comprising a pair of right triangular members made of metallic wires whose bases are in horizontal alignment and whose apexes at the acute base angles thereof are adjacent each other, the latter constituting connecting points for antenna wire leads, a first metallic strip parallel to said bases and connecting the apexes opposite said bases, a second metallic strip parallel to said first strip and terminally connected to the hypotenuses of said triangles and a network of crossed metallic Wires in each triangle effecting contact between the connecting point and the altitude thereof, the Overall length of said bases being 0.4m, the length of said altitudes being 0.16)\ 1O% and the space between said first and second strips being 0.014Ail0%, where A=wavelength in air at mean frequency, first harmonic, each non-conductive space in said network of wires having a dimension in any direction no greater than 0.L\i10% where t=wavelength in air at mean frequency, third harmonic.

References Cited in the file of this patent UNITED STATES PATENTS 2,175,253 Carter Oct. 10, 1939 2,614,220 Doerner Oct. 14, 1952 2,632,849 Fyler Mar. 24, 1953 2,656,463 Woodward Oct. 20, 1953 FOREIGN PATENTS 1,001,357 Germany Jan. 24, 1957 

